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Tesla is among the automakers staying ahead of the trend. While McKinsey projects that battery pack prices will be below $190/kWh by the end of the decade, Tesla claims to be below $190/kWh since early 2016.

That’s how the automaker manages to achieve close to 30% gross margin on its flagship electric sedan, the Model S.

This is the first big project from Tesla and SolarCity since the acquisition. Both companies believe this station is the biggest combination solar panel and storage facility in the world. With approximately 55,000 solar cells spread over about 45 acres, it’ll be tough to find anything larger.

But prices for lithium-ion batteries have fallen fast—by almost half just since 2014. Electric cars are largely responsible, increasing demand and requiring a new scale of manufacturing for the same battery cells used in grid storage. California is mandating that its utilities begin testing batteries by adding more than 1.32 gigawatts by 2020. For context, consider this: In 2016, the global market for storage was less than a gigawatt.

Tentative Conclusion: The battery is right on the verge of being cost effective to buy across most of the US for day/night arbitrage. And it’s even more valuable if outages come at a high economic cost.

All of the calculations are for energy, not power. In other words, you might produce 2400 MWh per day, but that doesn’t mean you’ll always have 100 MW available at any given instant. Sometimes you’ll generate more, other times less. Obviously there will be no solar production at night and less wind production on calm days. To be fully off-grid, Tesla will need some form of storage. As I surmised in a previous article, Tesla is probably shooting for more than the EV market; it seems logical for them to be looking into grid-level storage as well. What better way to showcase that than to include Li-ion batteries for on-site storage?

So far, SolidEnergy has made small, hand-built battery cells, similar to what you would find in a cell phone, using equipment and experts at an A123 Systems lab near Boston. (A123 Systems went bankrupt last year, and was acquired by the Chinese company Wanxiang.) These experimental cells store 30 percent more energy than conventional lithium-ion batteries, but the company calculates that the approach could eventually lead to a 40 percent improvement.

When the researchers tested the coated material they found that it had chemically stabilized the silicon surface. When they used it to make supercapacitors, they found that the graphene coating improved energy densities by over two orders of magnitude compared to those made from uncoated porous silicon and significantly better than commercial supercapacitors.

The resulting material displays all the electrical properties associated with a capacitor, meaning that it can charge and discharge its full capacity almost instantly. But it has a storage density that’s right at the low-end of the range seen in lead-acid batteries. It’s also stable over multiple charge/discharge cycles and holds on to 90 percent of its capacity even after being charged for 300 hours straight.

Current phones generally use only one antenna taking one stream of data at a time. LTE Advanced devices will also need more energy storage to do the necessary onboard computation. Without new breakthroughs in batteries or reductions in power consumption by other means (see “Efficiency Breakthrough Promises Smartphones that use Half the Power”), phones will simply get larger.

Some of the most promising battery chemistries—which, in theory, could store several times more energy than today’s lithium-ion batteries and cost much less—have a fatal flaw. They can’t be recharged very often before they stop working, making them useless for applications such as electric vehicles. Now researchers at Stanford have created novel nanostructures that greatly increase the number of times one of these chemistries can be recharged, even to levels high enough for many commercial applications.

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